Endoscopic surgical techniques have gained wide acceptance among surgeons and the patient population. There are many benefits associated with the use of endoscopic surgical techniques when compared to conventional, open surgical techniques. The benefits include reduced avenues for infection, reduced trauma to the patient, reduced hospital stay and a decrease in postoperative recuperation time, and decreased scarring. Accordingly, endoscopic surgical instruments have been developed for use in these endoscopic surgical procedures. Endoscopic as used herein is defined to include endoscopic, arthroscopic, laparoscopic and thoracoscopic.
Conventionally, in order to treat certain conditions involving ulcers of the stomach and duodenum, it has been necessary to perform an operation known as truncal vagotomy. It is believed that such ulcers are attributable to excess secretion of acid by the stomach. This excess stomach acid (over and above the quantity needed for normal digestion of food) attacks the lining of the stomach and the lining of the upper duodenum. In order to remediate this condition, the vagus innervation of the stomach is interrupted by the performance of the truncal vagotomy. When performing a truncal vagotomy it is also necessary to perform a drainage procedure. A pyloroplasty is one type of drainage procedure. The pyloroplasty ensures drainage of the gastric antrum following vagotomy and therefore partially eliminates the antral phase of gastric secretion. A pyloroplasty is a surgical procedure which involves the reshaping of the pylorus and the subsequent attachment of the lower part of the stomach proximal to the pylorus to the anterior portion of the duodenum distal to the pylorus. The attachment, i.e., closure, is made adjacent to either side of the reshaped pylorus. In the past, this operation has been performed using conventional, open surgical techniques, for example, the Heineke-Mikulicz pyloroplasty or the Finney pyloroplasty. In these techniques, the pyloric sphincter muscle is cut with conventional scalpels and then the stomach is sutured to the duodenum or the stomach and duodenum are closed in the direction opposite to which it is opened. More recently, circular staplers have been developed to perform a pyloroplasty/pylorectomy. The circular staplers simultaneously cut out a section of the pylorus while stapling the stomach to the duodenum.
It has now been found to be advantageous to perform a pyloroplasty/pylorectomy using endosurgical techniques. When performing an endoscopic pyloroplasty/pylorectomy, typically, a large diameter trocar is inserted through the abdominal wall and through the wall of the stomach into the interior of the stomach. Then, a conventional circular stapler particularly adapted to performing a pyloroplasty/pylorectomy is inserted through the trocar and to the site of the pylorus. The anvil and the staple cartridge head of the stapler are then maneuvered into the pylorus and positioned such that a section of the pylorus is removed as the distal part of the stomach is stapled to the proximal duodenum. Due to the nature of a circular stapler, or, as it is also known, an intraluminal stapler, it is necessary to shield off a portion of the opening or gap between the anvil of the stapler and the stapler cartridge when performing a pyloroplasty/pylorectomy so that the posterior wall of the pylorus will not be cut or stapled. When performing an anastomosis on tubular organs, the circular stapler is designed to cut a circular piece of the organ by making 360 degree incision. However, when performing a pyloroplasty/pylorectomy, it is neither desirable nor necessary to make a 360 degree cut which would remove the entire pylorus, rather it is desired to only remove a portion of the pyloric ring along a circular arc, e.g., about 90 degrees to 240 degrees. In order to accomplish this type of partial cut, it is necessary, as previously mentioned, to shield off a portion of the gap between the anvil and the staple cartridge.
A conventional circular stapler is designed to capture tissue in the gap between the distal anvil and the proximal staple cartridge, and to then engage the tissue and simultaneously cut and staple the tissue in the gap when actuated. In order to adapt the circular stapler for use in pyloroplasty/pylorectomy, a conventional pyloroplasty/pylorectomy shield was developed which is typically mounted to the circular stapler. The conventional pyloroplasty/pylorectomy shield consists of a proximal tubular member adapted to fit about the staple cartridge and a shield member extending distally from the tubular member and covering in part the gap between the anvil and the staple cartridge. In order to use a circular stapler which has been adapted for performing a pyloroplasty/pylorectomy, the anvil and staple cartridge, having a conventional pyloroplasty/pylorectomy shield mounted thereto, are positioned within a patient's pylorus. The section of the pylorus which is to be excised falls into the gap between the anvil and the staple cartridge. However, the shield prevents an arcuate posterior section of the pylorus from falling into the gap between the anvil and the staple cartridge, thereby preventing that portion from being cut and stapled by the circular stapler.
There are several deficiencies associated with a conventional pyloroplasty/pylorectomy shield. The conventional pyloroplasty/pylorectomy shield has a proximal tubular end which is loosely mounted to the staple cartridge. Since the proximal tubular end of a conventional pyloroplasty/pylorectomy shield is not rigidly attached to the staple cartridge, it is possible for the pyloroplasty/pylorectomy shield to pivot out of alignment or to rotate about the staple cartridge during insertion and positioning within the pylorus. This may result in staple misfiring with either no staple formation or poor staple formation. Or, it may result in misalignment and poor positioning of the pyloroplasty/pylorectomy.
Another disadvantage associated with a conventional pyloroplasty/pylorectomy shield is that the proximal tubular member is mounted to the cartridge of the stapler and the shield member extends axially and distally therefrom. Consequently, as the distal end of the stapler having the mounted pyloroplasty/pylorectomy shield is inserted into the stomach or through the pylorus, it is possible for the distal shield member of the pyloroplasty/pylorectomy shield to possibly pierce or damage the stomach wall, the pylorus, or the duodenum.
Another deficiency associated with a conventional pyloroplasty/pylorectomy shield used with a conventional circular stapler is that the contour of a conventional anvil head does not provide for progressive dilation of the pylorus. Conventional anvil heads have blunt distal surfaces or irregularly shaped distal surfaces or combinations thereof. Since the anvil contours are blunt and/or irregular, when the surgeon inserts the anvil through the pylorus the resulting dilation of the pylorus is sudden, possibly resulting in tears or damage to the pylorus.
Another deficiency associated with conventional pyloroplasty/pylorectomy shields relates to the length of the distally extending shield member. If the axial length of the shield member is too short, the back wall of the stomach or duodenum can become entrapped between the proximal face of the anvil and the distal edge of the shield member as the surgeon adjusts the gap between the anvil and the stapler cartridge in order to properly engage the tissue prior to performing the pyloroplasty/pylorectomy. This may result in injury to or perforation of the pylorus, stomach or duodenum. Conversely, if the shield member length is too long, then it may protrude a significant distance beyond the distal end of the anvil and can by its blunt, rough nature injure the back wall of the bowel as it is being introduced.
Yet another deficiency associated with the conventional pyloroplasty/pylorectomy shields used with conventional circular staplers is that, typically, a relatively large diameter stapler must be used to perform the anastomosis thereby aggravating the traumatic effects of pyloric dilation.
What is needed in this art is a pyloroplasty/pylorectomy shield which overcomes these deficiencies.